This is based on an overall figure of 49 g/km i.e. 80 g / mile (or 0.080 kg / mile) - from the AEA Report [23]. This gives a range from 19 g/km to 71 g/km for intercity trains depending on route, engine type (diesel or electric) and passenger load (ranging from 44% to 68%).

Allowance is needed for the fossil fuel used in oil exploration and refining (which is overall around 85% efficient - see car sources page), and for train and track manufacture and maintenance. So the figure of 80 g / mile is adjusted to 100 g / mile.

Other estimates

g / km

g / mile

Source

Notes

49

80

[AEA, 23]

The most detailed source, and the one used as a basis

49

80

[CG, 10]

Recommended by CG, summarising several sources

60

100

[NEF, 2]

60

100

[5]

60

100

[16]

giving DEFRA as the original source

70

110

[ML, 6]

(underground)

80

130

[MH, 3]

(underground / metro)

100

170

[MH, 3]

(intercity)

110

180

[ML, 6]

(intercity)

160

250

[ML, 6]

(other)

160

250

[MH, 3]

(other)

original source; after conversion

So the factor used by the Carbon Independent calculator is in the middle of the range of published estimates.